Can someone please walk me through this?-- 25 pts! Calculate the change of enthalpy for the reaction CH4 (g) + NH3 (g) --> HCN (g) +3H2 (g) from the following reactions:

Reaction 1: N2 (g) + 3H2 (g) --> 2NH3 (g); Change in enthalpy(∆ H): -91.8 kJ/mol

Reaction 2: C (s, graphite) + 2H2 (g) --> CH4 (g); Change in enthalpy(∆ H): -74.9 kJ/mol

Reaction 3: H2 (g) + 2C (s, graphite) + N2 (g) --> 2HCN (g); Change in enthalpy(∆ H): +270.3 kJ/mol

I have to include the following:

>The numerical answer with correct units.

>State which reactions, if any, you had to "Flip". ("Flipping" refers to modifying one of the reactions above to make a chemical be present on the other side-- like flipping an N2 that is on the reaction side. If it needs to be on the product side, you flip the reaction. Hope that makes sense.)

>State which reactions you had to multiply, if any, to get the correct amount of the compound. Also, include how much you multiplied the reaction by.

answer is: naturally occurring solid, inorganic compound or element is mineral.

minerals usually have crystalline form, that means than crystal constituents (atoms, molecules or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions.

for example magnetite is a mineral of iron oxide (fe₂o₃).

calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (caco₃).

dolomite is an   carbonate mineral composed of calcium magnesium carbonate (camg(co₃)₂).

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.

gasoline is a mixture. it contains several different kinds of compounds that can be present in a variety of ratios.